Facebook, Twitter and Google's YouTube say they are looking into reports that their sites have been blocked in Iraq as chaos grips the country.
"We are disturbed by reports of access issues in Iraq and are investigating. Limiting access to Internet services -- essential for communication and commerce for millions of people -- is a matter of concern for the global community," a Facebook spokesperson told CBS News.
Twitter issued a statement saying, "Users in #Iraq are reporting issues accessing our service. We're investigating their reports and we hope service will be restored quickly."
According to tech blogs such as Mashable and news organizations like Saudi-owned Al Arabiya, Iraq's Ministry of Communications has implemented a blackout of social media sites and mobile-messaging services WhatsApp and Viber.
Reporters in Iraq say email also appears to be down.
Reports of the outage come as Islamist militants in Iraq, under the command of the Islamic State of Iraq and Syria (ISIS), have steadily advanced their positions and expanded their control of territory.
Internet experts say social media can be a powerful propaganda weapon for extremists groups.
"Social media is also a double-edged sword. It can be used to promote democracy, but it can also be used to spread extremism," said Emily Parker, former State Department policy adviser and author of "Now I Know Who My Comrades Are: Voices From the Internet Underground."
This is not the first time that social media access has been disrupted amid turmoil in the Middle East region.
This March, Turkey blocked Twitter over recordings that appeared to incriminate Turkish Prime Minister Recep Tayyip Erdogan and other top officials in high-level corruption. Turkey's government restored access to the site in April after a high court ruling against the ban.